rename result.nix -> res.nix

also use `with nib.types`

nib/types/res.nix

@@ -0,0 +1,42 @@
+{nib, ...}:
+with builtins;
+with nib.types; rec {
+  # Res (Result) Monad
+  Res = success: value: {inherit success value;};
+  Ok = value: Res true value;
+  Ok' = Ok "ok";
+  Err = value: Res false value;
+  Err' = Err "err";
+
+  # Pattern Matching
+  isRes = R: attrNames R == ["success" "value"];
+  isOk = R: isRes R && R.success;
+  isErr = R: isRes R && !R.success;
+
+  # Unwrap (Monadic Return Operation)
+  unwrapRes = f: R:
+    if isErr R
+    then f R.value
+    else R.value;
+
+  # Map (Monadic Bind Operation)
+  mapRes = f: g: R:
+    if isOk R
+    then Ok (f R.value)
+    else Err (g R.value);
+  mapOk = f: mapRes f (x: x);
+  mapErr = f: mapRes (x: x) f;
+
+  # Conditionals
+  okOr = f: R:
+    if isOk R
+    then R
+    else f R;
+
+  errOr = f: R:
+    if isErr R
+    then R
+    else f R;
+
+  firstErr = findFirst isErr Ok';
+}